17(R)-Resolvin D3 (17(R)-RvD3) is an aspirin-triggered epimer of resolvin D3 .¹ It is produced from docosahexaenoic acid (DHA) by COX-2 in the presence of aspirin via a 17(R)-hydroperoxy DHA (17(R)-HDHA) intermediate and has been found in mouse inflammatory exudates.^1,2 17(R)-RvD3 reduces transmigration of isolated human polymorphonuclear cells (PMNs) and induces efferocytosis of apoptotic PMNs by macrophages.² 17(R)-RvD3 (10 ng/animal) reduces transmigration of neutrophils into the peritoneal cavity, as well as decreases the levels of IL-6 and increases the levels of IL-10 in inflammatory exudate in a mouse model of zymosan-induced peritonitis. It activates GPR32 in a β-arrestin reporter assay and increases phagocytosis to a greater degree in CHO cells overexpressing GPR32 compared to mock-transfected cells. 17(R)-RvD3 increases phagocytosis of etoposide-generated tumor cell debris by monocyte-derived macrophages in H460 human lung carcinoma cells in a concentration-dependent manner.³ It also inhibits tumor growth in a mouse model of Lewis lung carcinoma when administered at a dose of 0.6 µg/kg per day.